star wars - How did Darth Vader know the rebel base was on Hoth?

In The Empire Strikes Back, Darth Vader looks at a picture of a shield generator on an ice planet and declares that's the rebel base. How could he know merely by looking at the picture from the probe? In the movie, an imperial officer says the message from the probe was fragmentary, so that might be further reason to distrust it.

It was clear from A New Hope he did not have clairvoyance enough to find the rebels' hidden fortress.

Was there something in the novelization that said he had additional knowledge of Hoth?

Edit: I am not looking for an answer that merely says "He used the Force." The use of the Force to sense people seems inconsistent in the movies. Vader didn't sense Luke when he was standing outside the Millennium Falcon right after it was pulled into the Death Star. He didn't sense Leia when he captured her ship at the start of A New Hope. Count Dooku didn't sense Kenobi when Kenobi was hiding on Geonosis. Yet other times, people sense Force users who are light years away.

I am looking more for something that says Vader had actual information.

Answer

Anomalous life readings

“I think we’ve got something, sir,” Piett informed him. “The report is only a fragment from a probe droid in the Hoth system, but it’s the best lead we’ve had.”

Unimpressed, Ozzel snapped, “We have thousands of probe droids searching the galaxy. I want proof, not leads!” But Piett wasn’t finished. He added, “The visuals indicate life readings.”

“It could mean anything,” Ozzel said, growing impatient with Piett. “If we followed up every lead…”

“But sir,” Piett interrupted, “the Hoth system is supposed to be devoid of human forms.”

—The Empire Strikes Back (Junior Novelization)

This serves as a strong sign that something untoward is going on. As Piett later says, it could be smugglers, but Darth Vader is pretty confident that it is Luke.

They have images of Rebel snowspeeders

Yes, sir,” Piett said slowly, choosing his words with caution. “We have visuals. The system is supposed to be devoid of human forms. . .” But Vader was no longer listening to the captain. His masked face turned toward an image beamed on one of the viewscreens—an image of a small squadron of Rebel snowspeeders streaking above the white fields.

—The Empire Strikes Back (Novelization)

From the script, as well:

Vader moves to a large screen showing an image of the Rebel snow base. Rebel speeders can be seen approaching the base in the distance.

VADER: You found something?

PIETT: Yes, my lord.

It's unclear whether the snowspeeders have any markings or design elements indicating their Rebel affiliation, but they may. Alternately, the fact that a full squadron of speeders is present might tend to rule out smugglers, who might tend to have fewer members.

In that vein, the size of the base might be a clue as well that there is something more than smuggling going on. Also, the picture from the probe droid shows the power/shield generators quite clearly.

The monitor displayed the transmitted image of a snow-base power generator.

—The Empire Strikes Back (Junior Novelization)

These may well have been of the sort suitable only for a military installation, as opposed to a smuggler based unused to combat. Certainly if they could be recognized as shield generators, it would seem likely that the occupants of the base were more than mere smugglers.

The Force

True, Darth Vader's skill in the Force was not enough to simply pull the location of the base out of thin air.

As Admiral Motti says:

ADMIRAL MOTTI: Don't try to frighten us with your sorcerer's ways, Lord Vader. Your sad devotion to that ancient religion has not helped you conjure up the stolen data tapes, or given you clairvoyance enough to find the rebels' hidden fort-....

But it is possible that, with additional information (such as a picture of the Rebel base), the Force could provide him with sufficient intuition to know whether it was the right place or not.

“That’s it,” Vader said with conviction. “The Rebels are there.”

Admiral Ozzel saw nothing on the monitor that specifically indicated a Rebel presence, and he did not believe in expending time and energy on a mere hunch.

—The Empire Strikes Back (Junior Novelization)

This is also the impression conveyed by the The Empire Strikes Back: So You Want to Be a Jedi?, in which Vader can "sense" the presence of Luke and the Rebels, as mentioned in another answer.

Of course, Luke Skywalker was also at that base (which he was not in the previous case), and Force users have been shown to be able to sense the Force in others, albeit inconsistently.

VADER: That is the system. And I'm sure Skywalker is with them. Set your course for the Hoth system. General Veers, prepare you men.

This serves as further indication that it was Luke himself that Vader sensed.